The disclosure relates to message encoding. One claim recites an apparatus comprising: electronic memory for storing a plural-bit message; an electronic processor programmed for: obtaining a multi-bit seed; transforming the multi-bit seed by applying randomizing process; and encoding the transformed multi-bit seed with convolutional encoding, the encoded seed comprising a key for transforming the plural-bit message, the key providing security for the plural-bit message. Of course, other claims and combinations are provided too.